Delayed pulse generator



April 15 1952 H. SIMON Erm. GENERMIQ.

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Patented Apr. l5, 1952 y 2,592,611 "DELAYED PULSE GENERATOR Harry Simon, Baldwlnsvllle, and Joseph P. Gleason, Syracuse, N. Y., assiznors to General Electric Company, 'afcorporaton of New York Application September 29, 1950, Serial No. 187,584

This invention relates to the production of electrical pulses that are time delayed an adjustable amount with respect to the time `occurrence of reference pulses. f l

An object of the invention is to providan improved means for producing an electricalpulse that is delayed with respect to a referencezpulse.

Another object of the invention is to provide an improved means for producing a plurality of electrical pulses having diiferent delay times with respect to a reference pulse.

A further object of the invention is to provide an improved means for starting and stopping oscillations in a resonant circuit. 1 I,

A still further object of the inventionis to provide means for starting and stopping oscillations in a plurality of differently tuned circuits under control of a common switching arrangement. :I

According to one preferred embodimentofthe invention, a resonant circuit of series connected inductance and capacitance elements isjshock excited by rendering a gaseous discharge device operative in response to a reference pulse. The resultant oscillation is utilized to produce.' an output pulse delayed with respect to the time of occurrence of the reference impulse. VThe oscillation is also employed for rendering theV gaseous device inoperative.

The novel features which I believe characteristie of my invention are set forth with particularity in the appended claims. itself, however, both to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 shows an embodiment of my invention; Fig. 2 illustrates certain characteristics of its operation; Fig. 3 shows a modification, and Fig. 4 illustrates certain characteristics of the operation of the form of the invention illustrated in Fig. 3.

Referring to Fig. 1 there is disclosed a arrangement for forming an output pulse having an accurately controllable time delay with respect to an initiating or reference pulse. Brieily, the circuit comprises a gaseous discharge 'device I having a serious resonant circuit 2, 3 connected between its anode and cathode. The inductance 3 of this circuit is connected between the grid and cathode of a second discharge device 5 to supply oscillations thereto. This device 5 is a highly evacuated electron discharge device which is supplied with anode operating voltage from My invention circuit' 5 Claims. (Cl. Z50-27) source I2 through resistance II. Condenser 20 and resistance I9 are connected between its anode and cathode and the point between them is connected to the output or load circuit, not shown. The elements 20 and I9 serve as a differentiating circuit as will presently be described. Under normal conditions with no incoming trigger lpulse 4 being available, gaseous discharge device I, having its gaseous discharge path connected between ground and the battery 1, is normally held non-conductive by the application of a negative bias applied from battery 8 through resistor 9 to its grid electrode I0. Under these conditions, the condenser 2 is charged to approximately the full potential of battery 1.

Device 5, having its electron discharge path connected through the anode loading resistor II to a source of positive potential I2, is normally conductive because its grid electrode I3 is tied through the relatively low direct current resistance of inductance 3 to the cathode electrode I4. Upon the arrival of a positive trigger pulse 4 over` condenser I5 to the control grid I0, the gaseous discharge device I is rendered operative to conduct heavily, thereby shock exciting the series resonant circuit 2, 3 into oscillation by causing the charge previously developed across condenser 2 to discharge into the inductance 3 through the gaseous discharge path of device I. The resultant current flow `through inductance 3 is of a sinusoidal nature for substantially a quarter cycle at the series resonance frequency of elements 2 and 3. The corresponding sinusoidal voltage developed across inductance 3, that is, between terminal I6 and ground, leads the4 current in the inductance by and has a sharp substantially instantaneously negative going pulse followed by a sinusoidal return towardzero voltage. The sudden negative going pulse of voltage occurring substantially at the commencement of conduction of device I immediately cuts oir electrons discharge device 5, thereby generating a positive-going voltage pulse at its anode electrode I1. Discharge device 5 remains nonconductive during substantially the entire negative polarity portion of the voltage available at` terminal I 6. This voltage exists for substantially a quarter cycle of the oscillation frequency determined by the values of condenser 2 :and inductance 3.

As soon as the voltage at terminal I6 and oscillation of the series resonant circuit provides a negative going trailing edge to the voltage Wave developed at anode which is delayed With respect to the arrival of the incoming trigger li.

Differentiation of the voltage Wave developed at anode by condenser 26 and resistor IS yields a negative going trigger pulse at ,the output lead. This nega-tive triggerfpulse. occurs "substantially Aa quarter (cycle at the oscillation frequency of elements 2 and 3 after the arrival oi the incoming trigger d at the grid lil of device i.

YIn order to generate additional delayed ,pulses it is necessary to render the gaseous discharge order to provide an additional pulse delayed differently'in.` time with 'respect' to the incoming trigger '4,' an radditionalseries` resonant circuit comprising condenser 2| and inductance 22 are added. This latter resonant circuit is tuned to -za. differentfrequency of oscillation from that to device non-conductive, therebypermitting'condenser 2 to charge up once again toxsubstanto cause device to cease conduction. Resistor 6 is suiiiciently large to prevent conduction of device Without the voltage stored in the series resonant circuit. Cut off of device places the series resonant circuit in positionA tobe shock excited by a subsequent trigger pulse 5.

Referring to 2, thenature of thewavc shapes encountered Vin the arrangement. of Fig.

1 are clearly disclosed. 'Upon the ,sudden con duction of the discharge device in response to the incoming trigger pulse fl, showninv graphic, a sinusoidal current oWs through elements 2 and 3 as shown in graph b for substantially` a quarter ofV a cycle of 'the' oscillation'frequencyV of elements V`2 'and 3. The resultantvoltage developed across the inductance 3V and hence avail,-l

able at the grid'of device 5 is shown :in graph c. It is `noted thatafter v.the substantially .instantaneous surge of negative voltage, the volte age' on the inductance leads the current :by 90.l The negative going pulse of voltagev shown in graphe 'immediately cuts off electron `discharge device 5, therebygenerating the positive vgoing,

square wave as shown., in graph d atrits-anode electrode |1. As soon as'the voltage shown at c overcomes theV normal cuto bias of device 5,

device 5 conducts, thereby terminating the posi--y tive going square wave shown at d. This sudf den conduction at the anode i7 of device ll occurring after a quarter cycle ofV oscillation of the series resonant circuit provides the negative ygoing trailing edge Iii-shown in graph d,y

which is delayed with respect to the arrival Vof theV incoming trigger d. Upon diierentiation. the positive going square Wave shown in graphd yields the sharp negative trigger pulse iSd.:- This negative going pulse constitutes atrigger:

pulse, occurring at a denitedelay `time'afterthe arrival of incoming trigger pulse d, for apv plication to succeeding stages. v Fig. 3 .shows a modification'of lthe 'circuit arrangement of Fig. `:llwhich klends itselireadily. to the generationof a plurality-oi outputpulses delayed differently intime With respect tothe time of arrival of the incoming trigger.

, tially the potential of battery ythrough resistance 6 before the arrival of asubsequent'trigger the Vsingle triode shown in Fig. 1.

which the series arrangement comprising elements Zand 3 is tuned. A double triode circuit comprising electron discharge devices 23 and 24 is utilized in place of is connected to a control electrode 25 of electron discharge device 23, While a corresponding terminal V26 in the series resonant 'Y circuit comprising elements 2| and 22 is connected to the other control electrode 2170i' device 24. The anodes 23 and 29`are connected through respective anode loading resistors 3|] and 3|"to the source` of positive potential 32.-

Under vnormal conditions, device Vis nonconductive because its gridelectrode It is connected to the sourceof negativeY potentiall 8 through fresistance 9, whereas devices 23 and 2d are held conductive because their respective grids are returned to the common cathode through the relatively low direct vrcurrent resistance paths of inductances 3 and 22V respectively. Under these conditions condensers 2 and 2| are normally charged to substantially the full potential offbattery` l.

AUpon arrival of the incoming trigger gaseous discharge device I is rendered conductive thereby initiating oscillations in the series resonant circuits comprising devicesZ and 3, and 2|. and 22 through thegaseous discharge path of device l; The voltages. developed across vthe respective inductances-comprise a sharp instantaneous `negative goingpulse followed by a sinusoidal re turn to Zero at a rate dependentupon the resonance frequencies of the respective series reso nant circuits. The instantaneous negative going voltages now available at'terminals IB and 26,

and hence also at control electrodes 25 and 21,`

render devices 23 and 24 nonconductive, thereby developing arsudden rise in potential at the anodes 28 and 29 substantially at the `time of arrival of the incoming trigger 4. After Ysubstantially a quarter cycle of oscillation of `the,

. voltage atjterminal I6, devicer23 is again rendered conductive, thereby providing a sudden drop in the voltage at its anode. At a time corre-l spondingjto-substantially a quarterrcycle of the voltage availablev at terminal 26, the device 24 isalso rendered conductive, thereby generating a corresponding sudden dropin voltage at'wits anoleg29. Since the series Vresonant* circuits comprising elements 2|, 22 and 2fand 3 are arranged to have different oscillation frequencies,

Ythe positive going square waves developed at anodes 28 and29 are ofa diierent time duration..V Condensers 33 and V31|' together with ay common. load resistor 35 constitute separate differentiating circuits forthe voltagesdeveloped at anodes 2'8` and 2i)l to ."yield negative going pulseszhaving a diierent delay v'vith"res'pectv to the arrival of trigger pulses 4 in accordance with the? oscillation frequencies `of the: respective series resonant circuits.

Terminal I6 i and 2', 3, are employed with a common gaseous discharge device, the currents :flowing through each add alegebraicallyV and the resulting sum flows through the gaseous discharge device until one or both currents are interrupted by the switching devices '23V or 24. As long as the algebraic sum of the currents is of suiicient magnitude and in the right direction the device I conducts. Thus when the grid 21 of device 24 goes positive after a quarter cycle ofthe resonant frequency of elements 2| and 22, device 21|v conducts and current flow through 2| and 22 3 are tuned to a lower resonant frequency than elements 2|, and 22, then the grid 42li of device s 23 goes positive sometime subsequent to that of grid 2l and that electron discharge device 23 conducts thereby halting current ilow through elements 2 and 3. Thus even with no current flow through 2| and 22, sufficient charge exists on condenser 2 during the rst quarter of its oscillation to sustain conduction of thyratron Due to a finite grid to cathode impedance of de vices 23, condenser E is actually charged slightly negatively when the device 23 conducts, thereby insuring that the gaseous device is cut oir after the second delay pulse has been generated. If it is desired to increase the negative charge on condenser 2 at the end of a quarter cycle of oscillation of elements 2 and 3, a grid resistor 31 may be inserted between junction it and grid 25. The addition of the resistor also increases the positive overshoot of the voltage at grid 25.

Referring to Fig. fi, thc voltage wave shapes developed across the respective inductances 3 and 22 upon conduction of device I are shown in graph c. In this Fig. 4 voltage is plotted as ordinates against time plotted as abscissae. The voltage Wave available at terminal I6 is shown in heavy line inthe graph c, whereas the voltage wave developed at terminal 25 is shown in dotted line in the graph c. These voltages are developed in response to the current now shown in corresponding lining in graph b. The sharp negative going pulses of the voltages shown in graph c cut oi corresponding devices 23 and 24, thereby developing the positive going square waves at the anodes 28 and 29 shown in graph d substantially at the time of arrival of the incoming trigger' 4. As soon as the voltages developed across inductances 3 and 22 go positive as shown in graph c, the corresponding devices 23 and 24 are renderedconductive thereby generating a sudden drop in voltage at their respective anodes as shown in graph d The voltage waves shown in graph d in solid and dotted line are developed at the anodes 2S and 2B respectively.

Upon differentiation of the wave shapes shown in graph d the negative going trigger pulses shown in graph e are provided. It should be noted that the negative going `pulses shown in e occur at the time intervals 38 and 39 and correspond to definite delay time intervals with respect to the time ci arrival of the incoming trigger 4 depending upon the resonance frequencies of the associated series resonant circuits.

Although the circuit arrangement of Fig. 3 discloses the use ci two series resonant circuits lfor providing a pair of differently delayed output pulses, a plurality of such networks may be employed together with respective output electron discharge devices for generating the vari ous pulses.

An adjustable delay is attainable by using permeability tuned coils, although a variable capacitor would also give a variable delay. It should be noted that these results are achievable with a minimum of components, while requiring a minimiun of modication or adjustment to provide additional pulses having delay times that are selectable.

I have shown only certain preferred embodiments of my invention by way of illustration. Many modifications will occur to those skilled in the art and I therefore wish to have it understoodA that I intend in the appended claims to cover all such modifications as fall Within the `true spirit and scope of my invention.

What I claim` as new and desire to secure by Letters Patent of th-e United States is:

v1. In combination a series resonant circuit comprising an inductance and a capacitance, a nor-- mally inoperative switching device connected across said circuit, means for operating said device to shock excite said circuit thereby to produce an oscillation at the resonant frequency thereof, means responsive to said oscillation for generating an impulse delayed with respect to the time of excitation of said circuit, and means responsive to said oscillation to restore said switching device to its condition prior to said operation.

2. In combination a circuit comprising an in ductance, a capacitance and a source oi xed unidirectional potential connected in series, said inductance and capacitance being series tuned to a given frequency, a normally inoperative electron discharge device having its electron discharge path connected across said condenser and inductance, means for shock exciting said condenser and inductance into oscillation through the electron discharge path of said device comprising means for rendering said device operative. means for generating an impulse delayed with respect to the time of excitation of said inductance and capacitance in response to said oscillation, and means for rendering said device inoperative in response to said oscillation.

3. In combination a circuit comprising an inductance, a capacitance and a fixed unidirectional potential source connected in series, a normally inoperative electron discharge device having its electron discharge path connected across said inductance and capacitance whereby said capacitance is normally charged substantially to the potential of said source, a normally conductive electron discharge device comprising an input circuit connected directly across said inductance and an output circuit, means for shock exciting said capacitance and inductance into oscillation at the series resonant frequency thereof,y cornprising means for rendering said electron discharge device operative, said second device responsive to the voltage devoloped across said inductanc-e for generating an impulse delayed with respect to the time oi said excitation, and means for rendering said device inoperative in response to said oscillation.

4. In combination a plurality oi circuits each comprising a series connected condenser and inductance, means for charging each of said capacitances from a fixed unidirectional potential source, a common, normally inoperative, gaseous discharge device connected in parallel across each of said series circuits, a respective electron discharge device for each of said series circuits comprising an input circuit connected across a re spective inductance and an output circuit, means for rendering said gaseous discharge device operative to thereby shock excite each of said series circuits vinto oscillation at their respective series resonant frequencies through the gaseous discharge path of said device, each of said respective devices responsive to the voltage developed across a respective inductance for producing an impulse inthe output circuit delayed with respect to the time of excitation of said series circuits, and means for rendering said gaseous discharge device inoperative in response to the-oscil- 1 lations produced in the series circuit having the lowest resonant frequency.

5. In combination a series resonant circuit comprising an inductance and a capacitance, means for charging said capacitance to a given potential, a normally non-conductive gaseous dischargeY device having its gaseous discharge path connected across said series circuit, an impulse source, said gaseous device responsive to said impulse for becoming conductive to shock excite said series circuit into oscillation through its gaseous discharge path, a normally conducting electron discharge device having an input circuit connected across said inductance and an output circuit, said electron device being responsive to the oscillation developed across said inductalnce for becoming non-conductive for substantially the rst quarter cycle of oscillation of HARRY'SIMON. JOSEPH P. GLEASON.

No references cited. 

